I think, solve this problem. Don't know Deutsch, maybe already answered.
I've got topic problem when I trying to install by install.php and after filling form. After receiving this "unexpected error", I manually created a database, but without tables in it. Problem disappear.
But when I also created tables manually (just investigation), I've got a lot of "unexpected" errors and list of sql requests in the end.... So, this is wrong decision.
Try just create void database in your SQL server.